Graphite with/without silicon infiltration were oxidized at temperatures of 500 ℃, 700 ℃, 900 ℃ and 1 100 ℃, respectively, and the influence of silicon infiltration on the oxidation behavior of isostatic graphite was studied. SEM was adopted to characterize the surface and interior morphology. The pore structure of graphite was characterized by mercury intrusion porosimetry, and the mechanical properties of samples were measured. Results show that there is no obvious oxidative mass loss of samples at the temperature of 500 ℃. At the temperature of 700 ℃，the mass loss of graphite increases with the oxidation time, while no obvious mass loss is detected for the graphite with silicon infiltration. Moreover, the graphite with silicon infiltration maintains the high strength after oxidized at 700 ℃, but the strength of graphite without silicon infiltration significantly decreases and the bulk graphite even becomes powders. Therefore, the silicon infiltration can significantly increase the strength of graphite while improving its oxidation resistance.